The present invention relates to improved cementing compositions and their use in cementing operations, particularly for cementing wells penetrating subterranean formations.
In particular, the present invention relates to additives to cementing compositions employed in the cementing of oil and gas wells, for the purpose of reducing fluid loss from the cementing composition to the surrounding subterranean formation which the well has penetrated.
More particularly, the present invention relates to methacrylamidopropyltrimethylammonium chloride polymers as fluid loss additives to aqueous hydraulic cement slurries and the use of such slurries in well cementing operations.
Polymer compositions have long been used as additives to cementing compositions for the purpose of reducing water loss. For example, U.S. Pat. No. 2,614,998 discloses the use of water-soluble alkali salts of partially hydrolyzed polyacrylamide and polyacrylic acid for reducing the filtration of water from cement slurries. U.S. Pat. No. 3,359,225 describes the use of polyvinylpyrrolidone to prevent the separation of free water from a cement slurry to which it is added and U.S. Pat. No. 3,511,313 discloses a method for sealing void spaces in a geological formation with a liquid slurry of water swellable poly-N-vinyl pyrrolidone in an organo solvent therefor.